The term "open source" is widely applied to describe some software development methodologies. This paper does not provide a judgment on the open source approach, but exposes the fact that simply stating that a project is open source does not provide a precise description of the approach used to support the project. By taking a multidisciplinary point of view, we propose a collection of characteristics that are common, as well as some that vary among open source projects. The set of open source

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... haracteristics we found can be used as a tick-list both for analysing and for setting up open source projects. Our tick-list also provides a starting point for understanding the many meanings of the term open source.